Glial-derived neurotrophic factor regulates intestinal epithelial barrier function and inflammation and is therapeutic for murine colitis.

Although enteric glial cells (EGCs) have been demonstrated to play a key role in maintaining intestinal epithelial barrier integrity, it is not known how EGCs regulate this integrity. We therefore hypothesized that glial-derived neurotrophic factor (GDNF) produced by EGCs might be involved in this regulation. Here we investigated the role of GDNF in regulating epithelial barrier function in vivo. Recombinant adenoviral vectors encoding GDNF (Ad-GDNF) were administered intracolonically in experimental colitis induced by dextran sulphate sodium (DSS). The disease activity index (DAI) and histological score were measured. Epithelial permeability was assayed using Evans blue dye. The anti-apoptotic potency of GDNF in vivo was evaluated. The expression of tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and myeloperoxidase (MPO) activity were measured by ELISA assay and/or RT-PCR. The expression of ZO-1, Akt, caspase-3, and NF-kappaB p65 was analysed by western blot assay. Our results showed that GDNF resulted in a significant reduction in enhanced permeability, inhibited MPO activity, IL-1beta and TNF-alpha expression, and increased ZO-1 and Akt expression. Moreover, GDNF strongly prevented apoptosis in vivo and significantly ameliorated experimental colitis. Our findings indicate that GDNF participates directly in restoring epithelial barrier function in vivo via reduction of increased epithelial permeability and inhibition of mucosal inflammatory response, and is efficacious in DSS-induced colitis. These findings support the notion that EGCs are able to regulate intestinal epithelial barrier integrity indirectly via their release of GDNF in vivo. GDNF is namely an important mediator of the cross-talk between EGCs and mucosal epithelial cells. GDNF may be a useful therapeutic approach to the treatment of inflammatory bowel disease.

Tetrandrine ameliorates dextran-sulfate-sodium-induced colitis in mice through inhibition of nuclear factor -kappaB activation.

BACKGROUND: Activation of nuclear factor (NF)-kappaB has been shown to play a critical role in the pathogenesis of ulcerative colitis (UC), and tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the Chinese herb Radix Stephania tetrandra, has been demonstrated to be a potent inhibitor of NF-kappaB activation. The purpose of the study was to investigate effects of tetrandrine on experimental model of UC. MATERIALS AND METHODS: Tetrandrine was administered in experimental colitis induced by dextran sulfate sodium (DSS). The disease activity index (DAI) and histological score were observed. NF-kappaB DNA binding activity was assessed by electrophoretic mobility shift assay. The expression of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta were measured by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. RESULTS: A significant improvement was observed in DAI and histological score in mice with tetrandrine, and the increase in NF-kappaB DNA binding activity, myeloperoxidase activity, IL-1beta, and TNF-alpha in mice with DSS-induced colitis was significantly reduced following administration of tetrandrine. CONCLUSION: The administration of tetrandrine leads to an amelioration of DSS-induced colitis, suggesting administration of tetrandrine may provide a therapeutic approach for UC.